A fluorescent lamp device generally comprises a fluorescent tube socket, a starter and a ballast. The fluorescent lamp starters has two different types which are respectively shown in FIGS. 1 and 2 of the attached drawings. In FIG. 1, the starter comprises a hermetic casing 11 inside which an inert gas, such as argon and neon, is filled. Two conductive elements 12 and 13 are mounted inside the casing. One of the conductive elements, represented by the reference numeral 12, is made of a bi-metal material which, when heated, undergoes deformation so as to be in physical contact with the other conductive element 13. In operation, the two conductive elements 12 and 13 are not in contact initially and once a voltage is applied to the two conductive elements 12 and 13, a glow discharge through the inert gas inside the casing 11 occurs. By the glow discharge, the conductive element 12 is heated and gradually deformed to contact the element 13. This establishes a closed circuit loop through a fluorescent lamp.
In FIG. 2, another type of fluorescent lamp starter is shown, wherein a capacitor of approximately 0.006 .mu.F, indicated by the reference numeral 14, is connected in parallel with the starter. The starter has a structure similar to that shown in FIG. 1, namely having a hermetic casing 11 inside which an inert gas is filled and two conductive elements 12 and 13 secured inside the casing 11 and in parallel electrical connection with the capacitor 14.
The starters may also be classified as 1P (for 10 W and 20 W fluorescent lamps) and 4P (for 40 W fluorescent lamp) which are respectively used in combination with two different ballasts respectively shown in FIGS. 3 and 4, in which S indicates starter, 18 fluorescent lamp and 19 ballast.
In FIG. 5, a more detailed diagram of the fluorescent lamp circuit of FIG. 4 is shown. When a voltage is applied on the terminals A' and B', an electrical potential is established between the elements 12 and 13 of the starter S, causing a glow discharge. After a 1 to 2 second time elapse, due to temperature raise caused by the glow discharge, the element 12 is deformed to contact the element 13, forming a closed circuit loop. This causes a current flowing through the electrodes 16 and 17 of the fluorescent lamp 18 to heat up the electrodes 16 and 17. Thereafter, the self-induced high voltage provided by the ballast 15 drives the electrons emitted from one of the heated electrodes 16 and 17 to move through the inert gas inside the fluorescent lamp 18 to reach the other electrode, forming a closed current loop, which includes the ballast 15, the electrode 16, the inert gas inside the fluorescent lamp 18 and the electrode 17. By this way, the free electrons impact the coated inside surface of the fluorescent tube and the inert gas and emit light.
Once the closed loop forming partly by the free electrons moving through the fluorescent lamp 18 is established, glow discharge no longer occurs inside the starter S. The bi-metal element 12 thus cools down and disengages from the fixed element 13.
Such a conventional circuit structure of the fluorescent lamps although having been used for quite some time has several disadvantages, such as:
(1) To allow the two conductive elements 12 and 13 to contact each other, it takes time to heat up the elements 12 and 13 and thus the lighting of the fluorescent lamp 18 is slow.
(2) The heating of the bi-metal element 12 of the conventional starters consumes energy.
(3) The reliability of the bi-metal switch of the conventional starters may be affected by external temperature and may malfunction due to metal fatigue.
(4) The switching of the bi-metal starter requires a minimum rating voltage to trigger the switching so that it does not work for voltage lower than the rating level.
It is therefore to provide a novel fluorescent lamp starter structure which overcomes the above-mentioned drawbacks of the conventional starters.